1. Field of the Invention
The present invention relates to a method of and an apparatus for determining a machining sequence for a wire-cut electric discharge machine, and more particularly to a method and an apparatus for determining a machining sequence in continuously machining a plurality of machining shapes.
2. Description of the Related Art
A wire-cut electric discharge machine performs machining of the machining shapes of parts, dies, etc. from a workpiece through respective machining stages such as rough machining, semi-finish machining, finish machining and cut-off machining. In each of these stages, the wire-cut electric discharge machine performs electric discharge machining by combining basic operations including an operation for sending a wire electrode from an approach start point (machining start hole) to an approach point, a contour machining operation for machining a contour of machining shape, and an evacuating operation for evacuating the wire electrode from an evacuation start point on the machining shape to an evacuation point.
On the aforementioned wire-cut electric discharge machine, when a plurality of machining shapes included in parts and dies are machined continuously, it is necessary to select the machining sequence of performing the machining stages such as rough machining, semi-finish machining, finish machining, and cut-off machining for each machining shape so that the sequence is optimum according to the object to be machined and the various machining conditions such as required machining accuracy and operation efficiency. Various machining sequences can be selected. For example, a machining sequence, in which the machining stages such as rough machining, semi-finish machining, finish machining, and cut-off machining are performed for all machining shapes, can be selected. Alternatively, a machining sequence, in which after one machining stage is executed for some machining shapes of the plurality of machining shapes, another machining stages are performed for other machining shape groups, may be selected.
FIGS. 9a and 9b and FIGS. 10a and 10b illustrates the machining sequences for the plurality of machining shapes in a case where two machining shapes are machined continuously. FIG. 9a shows a case where a machining shape S1 is machined in a machining sequence of (1) rough machining, (2) two cycles of semi-finish machining, (3) finish machining, and (4) cut-off machining. FIG. 9b shows a case where a machining shape S2 is machined in a machining sequence of (1) rough machining, (2) finish machining, and (3) cut-off machining.
When the aforementioned two machining shapes are machined continuously, FIG. 10a shows a machining sequence in which the machining shape S1 is first subjected to rough machining, two cycles of semi-finish machining, finish machining, and cut-off machining and then the machining shape S2 is subjected to rough machining, finish machining, and cut-off machining.
On the other hand, FIG. 10b shows a machining sequence in which after the machining shape S1 is subjected to rough machining, the machining shape S2 is continuously subjected to rough machining and finish machining, the machining shape S1 is subjected to two cycles of semi-finish machining, finish machining, and cut-off machining, and then the machining shape S2 is subjected to cut-off machining.
Concerning the machining sequence shown in FIG. 10a, there has been known a method for setting a machining sequence in which the machining sequences are classified into a plurality of patterns used as standards, and the standard machining pattern is used. FIG. 11 is a flowchart for illustrating a conventional method for setting a machining sequence using a standard machining pattern, and FIG. 14 is a view for illustrating this method. In FIGS. 11 and 14, the plurality of machining patterns used as standards are prepared in advance as the standard machining patterns. In the standard machining patterns, the sequence of performing the machining stages for each shape has been determined. In the process shown in FIG. 11, a standard machining pattern is selected (Step S11), a machining shape is selected (Step S12), and NC data are prepared (Step S13).
When a plurality of machining shapes included in parts and dies are machined continuously on the wire-cut electric discharge machine, the aforementioned method, in which a machining sequence is set by using a standard machining pattern, has a problem in that machining can be performed only in the sequence defined by the standard machining pattern prepared in advance, and an arbitrary machining sequence other than the standard machining patterns cannot be selected.
A change of execution sequence of basic operations constituting the machining stage has also been known, and the process therefor is shown in a flowchart of FIG. 12. FIG. 15 is a view for illustrating the process. In FIGS. 12 and 15, basic operations for one machining shape is selected (Step S21), operations to be changed are selected from the process of the selected basic operations (P in FIG. 15), the execution sequence of the operations is changed (Pxe2x80x2 in FIG. 15), the execution sequence of basic operations is changed (Steps S22 and S23), and NC data are prepared (Step S24).
However, the aforementioned change of basic operations is a change for one machining shape, and also a change for each machining stage, so that the execution sequence of the plurality of machining shapes and the execution sequence of machining stages of machining shapes cannot be changed. Therefore, the edition of machining sequence of continuously machining the plurality of machining shapes cannot be performed. That is to say, it is difficult to specify the execution sequence of the machining stages of rough machining, semi-finish machining, finish machining, and cut-off machining for any number of machining shapes.
Also, in the conventional setting of machining sequence, the existing standard machining patterns are normally used. For this reason, when a machining sequence other than the existing machining patterns is set, it is thought that a new machining pattern is prepared by forming NC data for each machining shape and registering it and by joining the registered NC data.
FIG. 13 and FIGS. 16a and 16b are a flowchart for illustrating the process for setting a machining sequence other than the existing patterns and views for illustrating the process, respectively. In order to edit a machining sequence using a machining pattern where the machining pattern shown in FIG. 16a does not exist, as shown in FIG. 16b, each machining shape is selected (Step S31), NC data are prepared for the selected machining shape (Step S32), and then the NC data are registered (Step S33). After the NC data are registered for all machining shapes, the NC data for machining the plurality of machining shapes can be formed by using these registered NC data (Steps S34 and S35).
Therefore, this method for setting a machining sequence has a problem in that the NC data must be registered in advance, so that the operation for preparing the NC data for wire-cut electric discharge machining is complex, and it is difficult to make a change with ease.
An object of the present invention is to provide a method of and an apparatus for determining a machining sequence of wire-cut electric discharge machining, in which a machining sequence for continuously machining a plurality of machining shapes can be altered easily. Particularly, the object of the present invention is to provide a machining sequence determining method and an apparatus for wire-cut electric discharge machining, in which a sequence of the plurality of machining shapes and a sequence of machining stages for the machining shapes can be altered.
The present invention can easily change a machining sequence in the case where a plurality of machining shapes are machined continuously, by editing a sequence of combinations of machining shapes and machining stages for the machining shapes.
The method for determining a machining sequence of a wire-cut electric discharge machining in accordance with the present invention can take two different modes. In a first mode, a plurality of standard machining patterns are prepared in advance, and a desired machining pattern is formed by altering the standard machining patterns. In a second mode, a desired machining pattern is formed by editing a sequence of combinations of a plurality of machining shapes and machining stages associated with a selected machining type.
The aforementioned two different modes, the first and second modes, can also be used for the apparatus for determining a machining sequence of a wire-cut electric discharge machining and a computer readable medium in accordance with the present invention.
The first mode of the method for determining a machining sequence of a wire-cut electric discharge machining according to the present invention comprises the steps of: preparing a plurality of machining patterns respectively defining combinations of machining objective shapes and machining stages for the machining objective shapes and a sequence of the combinations; selecting one machining pattern from the plurality of machining patterns; determining each of the machining objective shapes; explicating the selected machining pattern to enable to edit the sequence of the combinations; and editing and determining the sequence of the combinations in the explicated machining pattern.
Each machining stage is determined for each machining shape, and is selected from machining processes such as rough machining, semi-finish machining, finish machining and cut-off machining. In the so-called punch machining in which a portion where a machining shape is cut out of a workpiece is used as a product, cut-off machining is performed finally, while in the so-called die machining in which a remaining portion after a machining shape is cut out of a workpiece is used as a product, cut-off machining is performed initially.
Each machining pattern defines combinations of machining shape and machining stages for the machining shape and a sequence thereof. A plurality of machining patterns are prepared so as to be selectable. Also, the machining pattern may define the positions of the plurality of machining shapes on a workpiece. In determining the objective machining shapes, an operator can select the position of each machining shape on the workpiece.
The explication of the selected machining pattern enables to edit the sequence of combinations of the objective machining shapes and the machining stages for the objective machining shapes. An operator determines the machining sequence by editing the sequence of the explicated combination.
This results in an easy alteration of machining sequence in the case where a plurality of machining shapes are machined continuously.
The second mode of the method for determining a machining sequence of a wire-cut electric discharge machining according to the present invention comprises the steps of: preparing a plurality of machining types and machining stages for each of the machining types; selecting one machining type from the plurality of machining types; determining a plurality of machining objective shapes; explicating the determined machining objective shapes and the machining stages for the selected machining type to enable to edit a sequence of combinations of the machining objective shapes and the machining stages; and editing and determining the sequence of combinations of the explicated machining objective shapes and the machining stages.
The method in the second mode does not use the standard machining patterns which are used in the first mode. In the second mode, instead of using the standard machining patterns, the machining type of electric discharge machining is selected. This machining type of electric discharge machining is a basic type of machining method for machining individual machining shapes such as punching and die machining, or closed machining and open machining, and the aforementioned machining stages such as rough machining, semi-finish machining, finish machining, and cut-off machining are specified in advance for each of the machining types.
Therefore, in the method of the second mode, a machining type is selected for machining shapes, and then, like the first mode, the machining objective shapes and the machining stages for the selected machining type are explicated and a sequence of the combinations is edited, thereby alteration of machining sequence in the case where a plurality of machining shapes are machined continuously is made easy.
Like the method for determining a machining sequence, the apparatus for determining a machining sequence of a wire-cut electric discharge machining according to the present invention can also take two different modes in determining the sequence. The apparatus of the first mode defines a plurality of standard machining patterns in advance, and forms a desired machining pattern by altering the standard machining pattern, and therefore has means for realizing these processes. The apparatus of the second mode forms a desired machining pattern by altering the sequence of combinations of machining objective shapes and machining stages for a selected machining type, and therefore has means for realizing the process.
Further, the computer readable medium according to the present invention can take two different modes in determining the sequence, like the aforementioned method and apparatus for determining a machining sequence. The computer readable medium of the first mode stores data of machining patterns and programs for forming a desired machining pattern by altering the machining pattern selected from a plurality of standard machining patterns prepared in advance. The computer readable medium of the second mode stores programs for performing processes of forming a desired machining pattern by altering the sequence of combinations of machining objective shapes and machining stages for a selected machining type.
According to the present invention, the NC data can be prepared based on the standard machining pattern and also the unique machining NC data can be prepared in accordance with the know-how and ease-of-use of the user. Also, new machining operation which does not depend on the existing machining pattern can be performed easily.
Further, the preparation for performing the actual machining operation, which has conventionally been needed, is not required, and also the machining sequence can be checked. Further, the NC data need not be prepared for each of the plurality of machining shapes, and the NC data can be prepared by one process.